In recent years, the amount of information processing that is needed is increasing along with improvement of the information processing technology, development of the internet environment and the like. In such situation, data center business to install and operate electronic devices of such as a server for internet, data communication equipment, a fixed-line phone, a cellular phone and an IP telephone in a concentrated manner is being paid attention. Generally, a plurality of such electronic devices are housed in a rack or the like. Then, a plurality of such racks are installed in a server room.
Meanwhile, by heat from electronic devices, a room temperature in a server room rises. Accordingly, air-conditioning equipment is installed usually in a server room, and control of temperature is performed.
However, by progress of consolidation of electronic devices along with increase of the information processing amount and increase of heat released from each electronic device, a load of air-conditioning equipment which controls the temperature of a server room is becoming large. Accordingly, technologies aimed at a load reduction of air-conditioning equipment have been proposed.
For example, in Japanese Patent Application Laid-Open No. 2009-193244, there is proposed a cooling system that has a server rack into which a plurality of electronic devices are mounted, an evaporator which makes a refrigerant be vaporized by exhaust heat of the electronic devices, and a condensing unit installed in a place higher than the evaporator, and makes the refrigerant perform natural circulation using a difference in densities of the refrigerant in the vapor and liquid states.
In Japanese Patent Application Laid-Open No. 2009-193137, there is proposed a cooling system that houses a plurality of electronic devices with a fan, and includes: a cabinet having a front face and a back face that are open; and a rear door that is provided in the opening of the back face side of the cabinet, and capable of ventilation. Between the rear door and the electronic devices, there are arranged a plurality of fin-and-tube type evaporators that form a refrigerating cycle, and refrigerant pipes of a plurality of evaporators are provided corresponding to a plurality of electronic devices.